I would not do anything about it. They have a right to freedom of speech. I would not do anything to curtail it. You can encourage them to use better language, but I do not recommend punishing them if they use bad language. That would be similar to fascism. They are not your kids anyway. Only parents should reprimand kids if they use bad language.
There is no “right” to use foul language, or do anything evil for that matter. It doesn’t matter whether or not one is an adult or a child. Moreover, a nanny is placed in authority by the parents.
Now to the OP. Unfortunately, while it might be tempting to think that these children learned to speak like this at school, it may very well be the case that they speak like this because their parents speak like this in front of them. If that’s the case, you might want to talk to the parents about it, and tell them it disturbs you that the kids are using such language. They might figure out not to use such langauge around them.
Having said all this, “for Christ’s sake”, while not good, is rather mild in comparison to some vulgarities. “Whore” is a little more serious, and should be addressed. You have to pick battles wisely. You would do well to ask your confessor how to handle such a situation.
Another thing I should stress, is, don’t assume its only the males in the household that curse; you’d be surprised how many mothers curse more than their husbands.
I must disagree with those posters who say that you shouldn’t do anything if the parents don’t believe in disciplining the children. It is a great act of charity to correct them for what
are faults. Obviously, you have less means of doing so than if you were their parents, but that doesn’t mean that some mild punishment (in the case of the 11 year-old cursing at the video game, telling them to turn it off, for example) is not in order. There is nothing unreasonable in not wanting to hear profanities. It’s true, you’re not their parents, but that doesn’t mean you can’t tell them that it’s wrong.
Benedicat Deus,
Latinitas